An increasingly large number of analytical tests, procedures, and analyses (i.e., assays) must be performed each day on many kinds of liquid samples, including, but not limited to, aqueous biological fluids such as blood, serum, urine, cerebrospinal fluid, and the like, To effectively handle and meet critical laboratory needs, "dry chemistry" analytical elements used in these analyses should function rapidly, require minimal operator involvement, provide accurate and reproducible results, and reduce the severe fluid handling problems presented by the very nature of liquid samples.
Prior to the present invention, certain improved "dry chemistry" multilayer analytical elements were developed as described in U.S. Pat. No. 3,992,158 issued Nov. 16, 1976 to overcome many of the foregoing problems.
Nevertheless, large complex molecules and cellular structures contained in many aqueous liquid samples or used as reagents (hereinafter termed interactive compositions) in many liquid analysis procedures create particular difficulty in the design and development of "dry chemistry" analytical elements. These substances tend to clog and impede fluid flow in conventional liquid transport structures contained in many analytical elements.
The present invention provides a novel particulate structure for the transport or analysis of liquids which readily accommodates and transports many large, complex molecules and cells which may be contained in such liquids.